Router Line Card Interim Routing for Fast Network Convergence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional routers in packet networks take more than a second to respond to network characteristic changes, leading to mis-routing and potential packet loss, which is costly for applications like algorithmic trading.
Innovation Solution
Implementing a line card with bespoke hardware to run an interim routing process in response to network state updates, generating interim routes before receiving comprehensive routes, thereby reducing the delay in packet routing and minimizing mis-routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional routers use comprehensive routing processes run by shared routing processors, then routing accuracy is maintained, but response time to network state changes exceeds one second
Solution Approach 1:
The routing process is segmented into two distinct processes: a comprehensive routing process that maintains accurate routing tables, and an interim routing process that provides rapid response to network changes. The line card can execute the interim routing process independently using stored network state information, bypassing the need to wait for the shared routing processor to complete comprehensive routing calculations. This segmentation allows the system to maintain routing accuracy through the comprehensive process while achieving fast response through the interim process.
Solution Approach 2:
The line card stores complete local Forwarding Information Base (FIB) and network state information in advance, enabling it to independently execute the interim routing process immediately upon detecting a network state change. This preliminary preparation of routing data and independent execution capability allow the line card to generate interim routes without waiting for the shared routing processor, thus achieving sub-second response time while maintaining routing accuracy through the subsequent comprehensive routing process.
2Loss of time
If line cards execute comprehensive routing processes independently, then response time is reduced, but device complexity increases
Solution Approach 1:
The line card executes a simplified interim routing process that performs only the essential functions needed for rapid response: comparing received network state updates against stored network state information and generating interim routes based on these comparisons. This partial action approach provides sufficient response speed for critical network changes without implementing the full complexity of comprehensive routing processes locally, thus achieving fast response time while limiting the increase in device complexity.
3Speed
If line cards store complete local FIB with all routing entries, then routing decisions are faster, but memory requirements increase
Solution Approach 1:
The FIB is segmented into a complete local FIB stored at each line card for fast local routing decisions, and a global FIB maintained by the shared routing processor for comprehensive routing management. The complete local FIB contains routing entries necessary for rapid interim routing decisions, while the global FIB ensures overall routing accuracy. This segmentation allows each line card to have sufficient routing information for fast decision-making without requiring all line cards to store the entire global routing table, thus improving routing speed while managing memory requirements.
Data Source
Figure 1
Figure 2
AI summary
A line card for use in a router or packet switch is disclosed. A problem with conventional routers or packet switches is that they can take over a second to fully react to a network state update from another router or packet switch. Such network state packets are used in dynamic routing protocols intended to route packets around a failed or overloaded router. In operating in according with dynamic routing protocols, conventional routers or packet switches react to such network state packets by updating the routing tables used by the line cards to send packets, or data extracted from packets, to the egress port (often on a different line card in the router or network switch) appropriate for the destination address found in the packet. Any packets which arrive between the network state packet's arrival and the completion of the ensuing routing table update on the line cards, can be misrouted - which can cause them to be delayed or dropped by the network. The described embodiments address this problem by operating the line card to react to a network state update packet by running a restricted routing algorithm to provide interim routes whilst a conventional comprehensive routing algorithm runs in parallel to provide a comprehensive set of routes. In this way, a faster, if less thorough, reaction to the arrival of a network state update packet is provided, which reduces the risk of packets being misrouted whilst the network converges. The technique has application to any packet networks, but is especially useful in Internet Protocol packet networks or Multi-Protocol Label Switching networks.